Interior panels such as the instrument panel in a motor vehicle typically have a cast vinyl skin or sheet stock vinyl skin material backed by a semirigid polyurethane foam that is adhered to a rigid plastic retainer or insert that attaches to the vehicle structure. Rigid plastic HVAC (heating, ventilating, and air conditioning) ductwork and various assembly components such as a glove box door and HVAC vents are then added separately in post-production assembly lines. Where energy absorption is desired in the panel for passenger protection, energy absorbing foams of the expanded bead type are generally used behind the skin. There is also a desire to incorporate the plastic ductwork in some of the panels for space and cost saving reasons. The foams that are commonly used for energy absorption result from the processing of beads of expandable styrenic polymer materials. But this processing does not normally permit such ductwork to be integrally molded in place in the foam with the foam molded in a consistent or uniform surrounding manner nor can such foam be molded against the plastic skin or the plastic ductwork or the plastic insert and successfully adhere directly thereto during the foam molding process. As a result, where such expanded bead foam materials are used for energy absorption, the foam is made separately from the panel and then adhesively bonded to the skin, ductwork, and/or the insert resulting in additional tooling, material, processing steps, and cost.
Moreover, whatever foam material is used for energy absorption and where the ductwork is to be molded in the foam, the foam must somehow be prevented from entering the ductwork during the foaming process. This poses a problem of cost effectively preventing this either with tools and/or in the manner of molding with the ductwork in place. There is also the additional problem of ensuring the dimensional stability of the finished panel where expandable styrenic polymer materials are used.